Spectrally sensitized silver dye-bleach photographic elements

ABSTRACT

PHOTOGRAPHIC ELEMENTS USEFUL IN THE SILVER DYE BLEACH PROCESS AND CONTAINING A BLEACHABLE DYE IN ASSOCIATION WITH A SILVER HALIDE EMULSION ARE EFFICIENTLY SPECTRALLY SENSITIZED TO RECORD RED LIGHT WITH THE USE OF A S YMEMETRICAL THIACARBOXYALKYL AND ALKYLSULFATE SUBSTITUENT GROUPS, AND TO RECORD GREEN LIGHT WITH THE USE OF SYMMETRICAL OXACARBOCYANINE DYE WHOSE CATIONIC PORTION IS FREE FROM CARBOXYALKYL AND ALKYLSULFATE SUBSTITUENT GROUPS.

United States Patent 3,574,623 SPECTRALLY SENSITIZED SILVER DYE-BLEACH PHOTOGRAPHIC ELEMENTS Carl James Williams, Jr., Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, NY. No Drawing. Filed Aug. 19, 1965, Ser. No. 481,064 Int. Cl. G03c 1/76, 1/10 US. Cl. 96-73 12 Claims ABSTRACT OF THE DISCLOSURE Photographic elements useful in the silver dye bleach process and containing a bleachable dye in association with a silver halide emulsion are efficiently spectrally sensitized to record red light with the use Of a symmetrical thiacarbocyanine dye Whose cationic portion is free from carboxyalkyl and alkylsulfate substituent groups, and to record green light with the use of symmetrical oxacarbocyanine dye whose cationic portion is free from carboxyalkyl and alkylsulfate substituent groups.

This invention relates to improvements in color photography. One aspect of this invention relates to improved spectrally-sensitized photographic elements useful in processes wherein colored bleachable dyes associated with a silver halide emulsion layer are bleached imagewise in the vicinity of a silver image.

In a typical silver-dye bleach process, a multilayer element is provided comprising silver halide layers differentially sensitized to blue, green and red radiation and having in association therewith, respectively, bleachable yellow, magenta and cyan colored dyes. After exposure, these elements may be developed in a black-and-white silver halide developer solution to form low contrast silver images in the exposed layers. Subsequent to development, the element is subjected to one or more acidic bleaching solutions comprising an agent commonly referred to as a bleach catalyst. This bleach catalyst oxidizes the metallic silver formed during processing and in so doing is reduced. The reduced catalyst then acts to reduce the colored, bleachable dye to a colorless product, while at the same time the catalyst is itself oxidized back to its original state. If desired, the catalyst may be included in the element or in the developer rather than in the bleach bath. The element may then be fixed in a conventional fixing bath.

Commonly, bleach processes of this type utilize azo dyes which are reductively destroyed in the presence of the developed silver image. However, other types of dyes, e.g., certain anthraquinone and triphenyl methane dyes, may be used, depending on their ability to be reductively cleaved under the bleach conditions.

The reduction may be accomplished either by a stoichiometric reaction in acid solution with the photolytic silver acting as the reducing agent, or by the reduction of the dye by stannite or other reducing agent which is catalyzed by the silver. In order to increase the reducing power of the metallic silver, the acidic bleach solutions may contain complex formers for silver ion, e.g., thiourea, mercaptans and benzimidazoles. Processes have also been described in which the halogen ion serves as a complex former for the silver ion. In addition to the complex formers which act by diminishing the silver ion concentration in solution, certain compounds like phenazines, quinoxalines, oxazines and sulfonated anthraquinones catalytically accelerate the bleach process. Apparently these compounds, Which form reversible reduction-oxidation systems, are reduced at the surface of the metallic silver and their reduction products difiuse to the dye and reduce it while the catalysts are oxidized.

Some typical dyes which have been suggested for dyeblea-ch processes are:

Cyan colored.1=(4-sulfophenyl)-3-carboxy-4 [4 (8- acetamido-3,6-disulfo-1-hydroxy-2 naphthylazo) 2,5-dimethoxyphenylazo] 5 -pyrazolone (see US. Patent N=C-CO on 00m on lynoooHs ("3CH-N=N N= 0 i 0 on. HOsS sour Magenta colored.8-(4-acetamidobenzamido) 3,6-disulfo-2-(Z-ethoxyphenylazo) 1 naphthol (see French Patent 1,289,163).

Yellow colored.-1-(4-sulfophenyl)-3-hendecyl 4 (4- diethylaminophenylazo)-5-pyrazoline (see French Patent 1,289,163).

It has been found that bleachable dyes employed in association with silver halide emulson layers cause undesirable reduction in sensitivity in various ways, such as by desorbing spectral sensitizing dyes from the silver halide grains. Sensitivity of the emulsion layers is also frequently reduced because the bleachable dye is of a col r which is complementary to the light which the emulsion layer is to record. In addition, bleachable dyes cause undesirable fog in the emulsion layer, which results in undesirable bleaching of the dye in non-image areas of the record. It therefore appears highly desirable to provide improved spectral sensitization of dye bleach materials whereby improved sensitivity and reduced fog are obtained.

I have now found that silver-dye bleach elements of greatly increased sensitivity may be prepared by the 'use of certain red and green spectral sensitizers.

It is, therefore, an object of my invention to provide novel color materials which retain the inherent advantages of the silver-dye bleach processes While significantly increasing the speed of such elements. Another object of my invention is to provide novel red and green spectral sensitizing combinations for silver halide photographic layers utilized in silver-dye bleach color photography. A

3 further object of my invention is to provide a method of significantly decreasing the fog and increasing the sensitivity of silver halide emulsion layers used in silver-dye bleach color processes. Other objects will appear from the following description of my invention.

In one embodiment of this invention, dye bleach materials are provided comprising a silver halide emulsion layer coated on a support, said layer having in association therewith a bleachable cyan dye, said emulsion being sensitized to red radiation with a symmetrical thiacarbocyanine dye whose cation is free from carboxyalkyl and alkyl sulfate groups. Advantageously, the symmetrical thiacarbocyanine dyes employed herein have at least one N-substituted sulfoalkyl group, such as sulfoethyl, sulfopropyl, sulfobutyl, e.g., 3-sulfopropyl, 3-sulfobutyl and 4-sulfobutyl; and, said dyes are free from carboxyalkyl and alkyl sulfate groups. Useful symmetrical thiacarbocyanine dyes of this invention include those having the following general I ia I ia X wherein Z represents the non-metallic atoms necessary to complete a cyclic nucleus such as phenyl or naphthyl, which nucleus may be substituted, for example with halogen, e.g., chlorine or bromine, or sulfoalkyl; R represents a hydrogen atom, or a hydrocarbon substituent such as lower alkyl, e.g., methyl, ethyl, propyl or butyl, or an aryl group such as phenyl; R and R each represents a-lower alkyl group, preferably of from about 1 to 4 carbon atoms, free from carboxyl and sulfate substituents, and X represents an ion, such as bromide, chloride, iodide, benzenesulfonate, methylsulfate, p-toluenesulfonate, ethylsulfate, perchlorate, etc. Preferably, at least one of R and R represents a sulfoalkyl substituent, in which case the sulfo group is the anion. It has been found that the symmetrical red-sensitizing thiacarbocyanine dyes provides particularly useful sensitization in silver dye bleach materials in that they unexpectedly result in decreased fog and increased speed as compared to 'prior art dye bleach elements wherein the red sensitization is provided by closely related dyes, such as unsymmetircal carbocyanine dyes, or symmetrical thiacarbocyanine dyes which contain carboxyalkyl or alkyl sulfate substituents. It should be noted that improved results are obtained with dyes having the above formula wherein neither R nor R contain a sulfo group; however, still greater decreases in fog and increases in speed are achieved when at least one of R and R and preferably both R and R represent sulfoalkyl groups.

Preferably, the red sensitizers of my invention are utilized in combination with a supersensitizing concentration of a non-ionized trinuclear cyanine dye of the type described in Brooker and White US. Patent 2,739,964, issued Mar. 27, 1956. Dyes of this type, which contain no acid anion, may be represented by the general formula:

wherein R and R each represents an alkyl group, Q represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring including those of the indandione series, A represents a member selected from the group consisting of an oxygen atom and a sulfur atom, 11, m and d each represents a positive integer of from 1 to 2, and Z and Z each represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring.

In another embodiment of my invention, dye bleach materials are provided comprising a silver halide emulsion layer coated on a support, said layer having in association therewith a bleachable magenta dye, said emulsion being sensitized to green radiation with a symmetrical oxacarbocyanine dye Whose cation is free from carboxyalkyl and alkyl sulfate groups. Advantageously, the symmetrical oxacarbocyanine dyes employed herein have at least one N-substituted sulfoalkyl group, such as sulfoethyl, sulfopropyl, or sulfobutyl, e.g., 3-sulfopropyl, 3-su1- fobutyl and 4-sulfobutyl; and, said dyes are free from carboxy alkyl and alkyl sulfate groups. Useful symmetrical oxacarbocyanine dyes of this invention include those having the following formula:

wherein Z represents the non-metallic atoms necessary to complete a cyclic nucleus such as phenyl or naphthyl, which nucleus may be substituted, for example with halogen, e.g., chlorine, bromine or sulfoalkyl; R represents a hydrogen atom, or a hydrocarbon s-ubstitutent such as alkyl, e.g., methyl, ethyl, propyl or butyl, or a phenyl substituent; R and R each represents an alkyl group, preferably of from about 1 to 4 carbon atoms, free from carboxyl and sulfate substituents, and X represents an anion. Preferably, at least one of R and R represents a sulfoalkyl substituents, in which case the sulfo group is the anion. It has been found that the symmetrical green-sensitizing oxacarbocyanine dyes provide particularly useful sensitization in silver dye bleach materials in that they unexpectedly result in decreased fog and increased speed as compared to prior art dye bleach elements wherein the green sensitization is provided by closely related dyes, such as unsymmetrical carbocyanin'e dyes or symmetrical oxacarbocyanine dyes which contain carboxyalkyl or alkyl sulfate substituents. It should be noted that improved results are obtained with dyes having the above formula wherein neither R nor R contain a sulfo group; however, still greater decreases in fog and increases in speed are achieved when at least one of R and R and preferably both R and R represent sulfoalkyl groups.

Preferably the green sensitizers of my invention are utilized in combination with a supersensitizing concentration of a benzimidazolocarbocyanine dye of the type described in Jones U.S. Patent 2,945,763, issued July 19, 1960. Dyes of this type may be represented by the following general formula:

(A) 11-1 (BM-1 wherein R and R each represents an alkyl group, such as methyl, ethyl, ,G-hydroxyethyl, n-propyl, n-butyl, [3- carboxyethyl, 'y-carboxypropyl, 4-carboxybutyl, fl-sulfoethyl, -sulfopropyl, 'y-sulfobutyl, 4-sulfobutyl, etc. (e.g., an alkyl group containing from 1 to 4 carbon atoms), R and R each represents an alkyl group, such as methyl, ethyl, n-propyl, n-butyl, etc. (e.g., an alkyl group containing from 1 to 4 carbon atoms) or an aryl group, such as phenyl, 0-, mor p-tolyl, etc. (e.g., a mono-nuclear aromatic group of the benzene series), d and n each represents a positive integer of from 1 to 4 and X represents an acid radical, such as chloride, bromide, iodide, benzenesulfonate, p-toluenesulfonate, methylsulfate, ethyl Layer D-Green sensitive layer containing a magenta colored azo dye Layer BRed sensitive layer containing a cyan colored azo dye Support In these examples the magenta dye has the following formula:

S OaNa NHz SiOaNa I -OH Ho- I SO3Na S O3Na and the cyan dye has the following formula:

02115 0 H N=N N=NN=N SOaNa NaOaS- NHz SOaNa I SOaNa SOaNa I1T=N- a polyene chain of three carbon atoms connects two cyclic Example 1 nuclei which are identical in all respects and which contain a heterocyclic N atom, with the one exception that the heterocyclic N atom of the nuclei may contains different substituents.

The advantages of this invention are realized with dye bleach materials wherein a silver halide emulsion layer has in association therewith a bleachable dye. The bleachable dye may be in a layer contiguous to the desired emulsion layer. Preferably, the bleachable dyes are incorporated in the emulsion layer to eliminate light scattering by the emulsion, thereby improving image sharpness and the ability to reproduce fine detail. The invention is applicable to any bleachable dye which tends to cause fogging and desensitization of spectrally sensitized silver halide emulsions. It is especially useful with bleachable azo dyestuffs which contain a phenolic (including naphtholic) group.

This invention will be further illustrated by the following examples. The following basic elements are used in the examples below.

Element I.-RED SENSITIVE LAYER Layer A-Gelatin, 300 mg./ft.

Layer BRed sensitive silver bromoiodide emulsion, 162

mg. silver/fif cyan colored azo dye, 59 mg./ft. polya-methyl-allyl-N-guanidyl ketimine glycollate mordant (see US. Patent 2,882,156), 190 mg./ft. 6,7-dimethyl 2,3 dipyridylquinoxaline. 10 mg./ft. gelatin, 320

mg./ft.

Support Element II.GREEN SENSITIVE LAYER Layer AGelatin, 300 rug/ft.

Layer BGreen sensitive silver bromoiodide emulsion, 162 mg. silver/ft magenta colored azo dye, 62 mg./ ft poly-a-methyl-allyl-N-guanidyl ketimine glycollate mordant, 157 mg./ft. 6,7 dimethyl-2,3-dipyridylquinoxaline, l0 mg./ft. gelatin, 320 mg./ft.

Support Element III.TRI-COLOR ELEMENT Layer A-Gelatin overcoat Layer BBlue sensitive layer containing a yellow colored azo dye Layer CYellow filter layer N I 0112011200011 CHzCHzCOO Coating B* contained 200 mg. of the red sensitizer of my invention, anhydro 5,5 dichloro-3,9-diethyl-3-(3- sulfobutyl)thiacarbocyanine hydroxide per silver mole.

| CHzCHzCHCHg Coating 0' contained 200 mg. anhydro-5,5'-dichloro- 9 ethyl-3,3'-di-(4-sulfobutyl)thiacarbocyanine hydroxide per silver mole.

Coating D* contained 200 mg. anhydro-9-ethyl-3,3'- d1-(3 sulfopropyl) 4,5,4',5' dibenzothiacarbocyanine hydroxide, sodium salt per silver mole.

*iCoatings B, C and D contained dyes wilthin the scope of my invention.

7 Coating E contained 200 mg. anhydro-B-ethy1-5-phenyl- 1-(4-sulfobutyl)thia-4'-carbocyanine hydroxide per silver e N-H2000 Coating G contained 200 mg. of anhydro-S-B-carboxyethyl chloro-1'-ethylthia-4'-carbocyanine hydroxide,

semihydroiodide per silver mole.

CCH=CHCH= N-CzH -HI 01 ea/ These coatings were given a minus blue exposure through a Wratten #15 filter in an Eastman I-B sensi- -tometer and processed for three minutes in Kodak D72 Developer containing 2 grams of potassium thiocyanate and 0.05 gram of S-methylbenzotriazole per liter, followed by a two minute fixation in Kodak F-S Fixer. Dye bleaching was accomplished by thirty second immersion in a liter of solution containing 125 grams of thiourea, 100 ml. of concentrated hydrochloric :acid and 30 ml. of 0.1 percent solution of 2 hydroxy-3-aminophenazine (in waterzglacial acetic acid 1:1), followed by a three minute ferricyanide bleach and one minute fixation to remove excess silver. The minus blue characteristics of the silver (in the black-and-white developer) and the reversal curves thus obtained were as follows:

RED SENSI'IIZATION MINUS BLUE EXPOSURE [Black-and-white developer silver mg. lftfi] Contains dyes within the scope of my invention. Increased reversal DEF indicates lower fog.

Example 2 Five coatings of the type represented by basic Element H were prepared.

Coating A* contained 200 mg. of anhydro-9-ethyl-5,5'- diphenyl 3,3 di-(3 sulfobutyl)oxacarbocyanine hydroxide, m'onosodium salt, a dye within the scope of my invention, per silver mole.

Coating B contained 200 mg. of 3,3,9-triethyl-5,5'-

diphenyl-oxacarbocyanine iodide per silver mole.

Coating C contained 200 mg. of anhydro-l-ethyl-3-(2- sulfohydroxypropyl)thia-2'-cyaniue hydroxide per silver mole.

| C2115 CHzCH-CH; 08020 Coating D contained 200 mg. of anhydro-l-ethyl-3-(3- sulfohydroxypropyl)thia-2'-cyanine hydroxide per silver crncmomosoio Coating E contained 200 mg. of anhydro-l'-ethyl-3(3- sulfobutyl)thia-2'-cyanine hydroxide per silver mole.

mole.

CzHs

o-on= a N crrzornonom 9 S03 Samples of these coatings were tested as described in Example 1 to yield the following results:

GREEN SENSITIZATION, MINUS BLUE EXPOSURE [Black-and-white developer silver, mg./1t.

Image Reversal difierential, Rela- Rela- Maximaxitive tive mum Fog mum-fog speed D max. speed *Contained a green sensitlzer within the scope of my invention.

Example 3 Three additional coatings of the type represented by basic Element II were prepared.

Coating A was identical to Coating A of Example II.

Coating B contained 200* mg. of anhydro-3-ethyl-9- methyl-3-(3 sulfohydroxypropyl)thicarbocyanine hydroxide per mole.

Coatings A and B contained dyes within :the scope of my invention.

Coating C contained 200 mg. of anhydro-3-ethyl-9- methyl-3-(3-sulfopropyl)thiacarbocyanine hydroxide per silver mole.

2H5 z HzcHisos These coatings were given an exposure to green light through Wratten filters #61 plus #16 in an Eastman I-B sensitometer and then processed as described in Example 1 to yield the following results:

GREEN SENSITIZATION, GREEN EXPOSURE [Black-and-white developer silver, mgJftfi] Image Reversal differential, Rela- Rela- Maximaxitive tive mum Fog mum-fog speed Dam. Speed Coating:

A 90 24 66 100 0. 63 100 B 76 21 55 54 0. 71 80 C 85 25 60 60 0. 57 73 Contained a green sensitizer within the scope of my invention.

Example 4 CHaO CHzCHz-N N-CHzCHzOCHg Coating C contained 200 mg. of anhydro-5,S'-dichloro- 9-ethyl-3,3'-di-(4-sulfobutyl)thiacarbocyanine hydroxide per silver mole.

Coating D contained 175 mg. of anhydro-5,5'-dichloro- 9-ethyl-3,3'-di-(4-sulfobutyl)thiacarbocyanine hydroxide plus 17.5 mg. of 5-[di (1-ethyl-2(lH)-l3-naphtho-[1,2]- thiazolylidene)-isopropylidene] 1,3 di-(fi-methoxyethyl)barbituric acid per silver mole.

Samples of these coatings were tested as described in Example 1 and the following results were obtained:

RED SENSITIZAIION COMBINATION, MINUS BLUE EXPOSURE [Black-and-white developer silver, mgJftfl] Image Reversal difierential, Rela- Rela- Maximaxitive tive mum Fog mum-fog speed Dmax. speed Coating:

EXAMPLE 5 The effect of the combination of a benzimidazolocarbocyanine dye with the preferred green sensitizers is illustrated by the following examples.

Two coatings of the type represented by basic Element 11 were prepared.

Coating A contained 200 mg. of anhydro-9'-ethyl-5,5'- diphenyl-3,3'-di(3 sulfobutyDoxacarbocyanine hydro-xide, monosodium salt per silver mole.

Coating B contained 135 mg. of anhydro-9-ethyl-5,5- diphenyl-3,3'-di-(3 sulfobutyl)oxacarbocyanine hydroxixde monosodium salt plus 54 mg. of anhydro-5,5,6,6'- tetrachloro 1,1 diethyl-3,3-di-(3-sulfobutyl)benzimidazolocarbocyanine hydroxide per silver mole.

Samples of these coatings, when tested as described in Example 1, produced the following results:

GREEN SENSITIZATI%IPCO%MBINATION, MINUS BLUE URE [Blaek-and-white developer silver, mg.lft.

Image Reversal differential, Rela- Rela- Maximaxitive tive mum Fog mum-fog speed Din. speed Coating:

EXAMPLE 6 Two additional coatings of the type represented by basic Element II were prepared.

Coating A contained 200 mg. of 3,3',9-triethyl-5,5-diphenyl-oxacarbocyanine iodide per silver mole.

Coating B contained mg. of 3,3,9-triethyl5,5- diphenyl-oxacarbocyanine iodide plus 54 mg. of 5,5, 6,6 tetrachloro 1,l,3,3-tetraethylbenzimidazolocarbocyanine iodide per silver mole.

02115 CzHs I When samples of these coatings were tested in the manner described in Example 1, the following results were obtained:

GREEN SENSITIZATION COMBINATION, MINUS BLUE EXPOSURE [Black-and-white developer silver, mg. /ft.

Image Reversal difierential, Rela- Rela- Maximaxitive tive mum Fog mum-fog speed Din. speed Coating A 100 18 82 100 .85 100 B 105 2A 81 162 59 123 Example 7 To exhibit the eifect of my preferred dyes in multilayer elements in comparison to the use of prior art sensitizers in similar elements, the following experiments were performed.

Three coatings similar to basic Element III were prepared.

Coating A contained 200 mg. of the red sensitizer anhydro 9 ethyl-3,3-di-(3-sulfopropy1)-4,5,4,5-dibenzothiacarbocyanine hydroxide monosodium salt per silver mole in Layer E. It also contained 200 mg. of the green sensitizer anhydro 9 ethyl-5 ,5 -dipheny1-3,3-di-(3-sulfobutyl)oxacarbocyanine hydroxide monosodium salt per silver mole in Layer D. The dyes utilized in this element are Within the scope of my invention.

Coating B contained 175 mg. of anhydro-9-ethyl-3,3'- di (3 sulfopropyl) 4,5,4,5 dibenzothiacarbocyanine hydroxide monosodium salt plus 17.5 mg. of S-[di-(lethyl 2(1H) {3 naphtho[1,2]thiazolylidine)isopropylidene]-l,3-di-(,8-methoxyethyl)barbituric acid per silver mole in Layer E. It also contained 135 mg. of anhydro-9- ethyl 5,5 diphenyl 3,3'-di-(3-sulfobutyl)oxacarbocyanine hydroxide monosodium salt plus 54 mg. of anhydro- 5,5 ',6,6 tetrachloro 1,1 diethyl-3,3-di-(3-sulfobutyl) benzimidazolocarbocyanine hydroxide per silver mole in Layer D. The dye combinations utilized in this element are within the scope of my invention.

Coating C contained 200 mg. of the red sensitizer 3,3- di-fl-carboxyethylthiacarbocyanine bromide per silver mole in Layer E. It also contained 200 mg. of the green sensitizer anhydro-l'-ethyl-3-(3-sulfobutyl)thia-2-cyanine hydroxide per silver mole in Layer D. These dyes are outside the scope of my invention.

Samples of the above coatings were given a minus blue exposure through a Wratten #15 filter in an Eastman I-B sensitometer and then processed as described in Example 1. The fog values obtained in each coating were as follows:

Coating: Fog (Red+Green) A 0.25 B 0.14 C 0.39

It will be noted that Coating A which contained sensitizers within the scope of my invention exhibited significantly less fog than Coating C which contained dyes not included in the scope of my invention. Coating B, which contained red and green dye sensitizer combinations of my invention, exhibited an especially low fog level.

The sensitizing dyes employed in this invention may be used effectively over a wide concentration range, with best results at concentrations of about 10 to 250 mg. of dye per mole of silver halide. supersensitizing dyes are also effective over a broad concentration range, with especially good results being achieved at ratios of sensitizing dye to supersensitizing dye of about 1:5 to about 5:1, by weight.

The photographic emulsions used in my invention can contain additional conventional addenda known in the art such as chemical sensitizers, stabilizers, development modifiers, plasticizers, hardeners, coating aids, etc. Various silver salts may be utilized as the sensitive salt such as silver bromide, silver iodide, silver chloride or mixed silver halides such as silver chlorobromide, silver chlorobromoiodide or silver bromoiodide. The spectrally sensitized emulsions of my invention can be used in emulsions which form latent images predominantly inside the silver halide crystal, such as those described in Davey and Knott US. Patent 2,592,250 issued Apr. 8, 1952.

In the preparation of the silver halide emulsions of my invention, there may be employed as the dispersing agent for the silver halide grains, gelatin or some other colloidal material such as colloidal albumin, a cellulose derivative or a synthetic resin, for instance, a polyvinyl compound.

A variety of materials may be used as the support for the photographic layers of my invention. For example, cellulose acetate, polyethylene terephthalate, paper, glass or metal supports may be utilized.

The invention has been described in detail with particular reference to preferred embodiments thereof but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

I claim:

1. A photographic element comprising a support having coated thereon a silver halide emulsion layer,

formula:

N lite l h Xe wherein Z repersents the non-metallic atoms necessary to complete a cyclic nucleus selected from the group consisting of phenyl and naphthyl; R represents a substituent selected from the group consisting of hydrogen, lower alkyl and aryl; R and R each represents lower alkyl, said alkyl groups being free from carboxyl and sulfate substituents; and X represents an anion.

2. A photographic element comprising a support having coated thereon a silver halide emulsion layer, said layer having in association therewith an azo dye, bleachable in the silver dye bleach process, which tends to cause fogging and desensitization of said emulsion, said emulsion being sensitized to red radiation with a symmetrical thiacarbocyanine dye having the following formula:

in R1 wherein Z represents the non-metallic atoms necessary to complete a cyclic nucleus selected from the group consisting of phenyl and naphthyl; R represents a substituent selected from the group consisting of hydrogen, lower alkyl and aryl; R and R each represents lower alkyl, said alkyl groups being free from carboxyl and sulfate substituents; and X represents an anion, and containing a supersensitizing concentration of a trinuclear dye having the general formula:

I Z I wherein R and R each represents an alkyl group, Q, Z and Z each represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, A represents a member selected from the group consisting of an oxygen atom and a sulfur atom, and n, m and d each represents a positive integer of from 1 to 2.

3. A photographic element comprising a support having coated thereon a silver halide emulsion layer containing a bleachable cyan colored dye which tends to cause fogging and densitization of the silver halide emulsion, said emulsion being sensitized to red radiation with anhydro-9-ethyl-3,3-di-di(3 sulfopropyl)-4,5,4,5-dibenzothiacarbocyanine hydroxide.

4. A photographic element comprising a support having coated thereon a silver halide emulsion layer, said layer having in association therewith an azo dye, bleachable in the silver dye bleach process, which tends to cause fogging and densensitization of said emulsion, said emulsion being sensitized to red radiation with a symmetrical thiacarbocyanine dye having the following formula:

a In x wherein Z represents the non-metallic atoms necessary to complete a cyclic nucleus selected from the group consisting of phenyl and naphthyl; R represents a substituent selected from the group consisting of hydrogen, lower alkyl and aryl; R and R each represents lower alkyl, said alkyl groups being free from carboxyl and sulfate substituents; and X represents an anion, and containing a supersensitizing concentration of a trinuclear dye having the general formula:

wherein R and R each represents an alkyl group, Q, Z and Z each represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, A represents a member selected from the group consisting of an oxygen atom and a sulfur atom, and n, m and d each represents a positive integer of from 1 to 2.

5. A photographic element comprising a support having coated thereon a silver halide emulsion layer, said layer having in association therewith an azo dye, bleachable in the silver dye bleach process, which tends to cause fogging and densensitization of said emulsion, said emulsion being sensitized to red radiation with a symmetrical thiacarbocyanine dye having the following formula:

R I ia X wherein Z represents the non-metallic atoms necessary to complete a cyclic nucleus selected from the group consisting of phenyl and naphthyl; R represents a substituent selected from the group consisting of hydrogen, lower alkyl and aryl; R and R each represents lower alkyl, said alkyl groups being free from carboxyl and sulfate substituents; and X represents an anion, and containing a supersensitizing concentration of a trinuclear dye having the general formula:

wherein R and R each represents an alkyl group, Q, Z and Z each represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, A represents a member selected from the group consisting of an oxygen atom and a sulfur atom, and n, m and d each represents a positive integer of from 1 to 2.

6. A photographic element comprising a support having coated thereon a silver halide emulsion layer containing a bleachable magenta colored dye which tends to cause fogging and desensitization of the silver halide emulsion, said emulsion being sensitized to green radiation with anhydro 9-ethyl-5,5'-diphenyl-3,3'-di-(3-sulfobutyl) oxacarbocyanine hydroxide, monosodium salt.

7. A photographic element comprising a support having coated thereon a silver halide emulsion layer, said layer having in association therewith an azo dye, bleachable in the silver dye bleach process, which tends to cause fogging and desensitization of said emulsion, said emul- 14 sion being sensitized to red radiation with a symmetrical thiacarbocyanine dye having the following formula:

wherein Z represents the non-metallic atoms necessary to complete a cyclic nucleus selected from the group consisting of phenyl and naphthyl; R represents a substituent selected from the group consisting of hydrogen, lower alkyl and aryl; R and R each represents lower alkyl, said alkyl groups being free from carboxyl and sulfate substituents; and X represents an anion, and containing a supersensitizing concentration of a trinuclear dye having the general formula:

wherein R and R each represents an alkyl group, Q, Z and Z each represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, A represents a member selected from the group consisting of an oxygen atom and a sulfur atom, and n, m and d each represents a positive integer of from 1 to 2.

8. A photographic element comprising a support having coated thereon at least two silver halide emulsion layers, one of said layers containing a bleachable cyan colored dye which tends to cause fogging and desensitization of the silver halide emulsion, the silver halide of said layer being spectrally sensitized to red radiation with anhydro 9 ethyl-3,3'-di-di(3-sulfopropyl)-4,5,4',5'-dibenzothiacarbocyanine hydroxide; and said other layer having incorporated therein a bleachable magenta colored dye which tends to cause fogging and desensitization of the silver halide emulsion, the silver halide of said layer being spectrally sensitized to green radiation with anhydro 9 ethyl-5,5'-diphenyl-3,3'-di-(3-sulfobutyl)oxycarbocyanine hydroxide, monosodium salt.

9. A photographic element as described in claim 1 wherein the symmetrical thiacarbocyanine dye is selected from the group consisting of anhydro-5,5'-dichloro-3,9-diethyl-3'-(3-sulfobutyl)thiacarbocyanine hydroxide, anhydro-5,5-dichloro 9 ethyl-3,3'-di-(4-sulfobuty1)thiacarbocyanine hydroxide, and anhydro-'9-ethyl-3,3'-di-(3-sul fopropyl)-4,5,4,5-dibenzothiacanbocyanine hydroxide.

10. A photographic element as described in claim 2 wherein the symmetrical thiacarbocyanine dye is selected from the group consisting of anhydro-5,5'-dichloro-3,9-diethyl-3'-(3-sulfobutyl)thiacarbocyanine hydroxide and anhydro-5,5'-dichloro 9 ethyl-3,3-di-(4-sulfobutyl)thiacarbocyanine hydroxide and the trinuclear dye is 5-[di 1- ethyl 3(lH)-fl-naphtho-[1,2]-thiazolylidene)isopropylidene]-l,3-di-(,B-methoxyethyl)barbituric acid.

11. A photographic element as described in claim 4 wherein the symmetrical oxacarbocyanine dye is selected from the group consisting of anhydro-9-ethyl-5,5-diphenyl 3,3 di (3-sulfobutyl)oxacarbocyanine hydroxide, monosodium salt and 3,3,9-triethyl-5,5'-diphenyloxacarbocyanine iodide.

12. A photographic element as described in claim 5 wherein the symmetrical oxacarbocyanine dye is selected from the group consisting of anhydro-9-ethyl-5,5'-diphenyl 3,3 di (3-sulfobutyl)oxacarbocyanine hydroxide, monosodium salt, and 3,3,9-triethyl-5,5-diphenyloxacarbocyanine iodide and the benzimidazolocarbocyanine dye is selected from the group consisting of anhydro-5,5',6,6'- tetrachloro-l,1'-diethyl 3,3 di-(3-sulfobutyl)benzimid- 15 16 azolocarbocyanine hydroxide and 5,S',6,6-tetrachl0ro-1, 3,157,507 11/1964 Bruengger 96-99 1,3,3'-tetraethyl benzimidazolocarbocyanine iodide. 3,397,060 8/ 1968 Schwan et a1 96--104 References Cited NORMAN G. TORCHIN, Primary Examiner UNITED STATES PATENTS 5 M. F. KELLEY, Assistant Examiner 2,704,714 3/1955 Carroll et a1 96104 2,704,717 3/1955 Jones 96--104 96 99 2,739,964 3/1956 Brooker et a1. 96105 

